Gas-electric highbred vehicles are now being developed in order to promote conservation of nature. Such a gas-electric highbred vehicle is provided with two kinds of batteries. One of them is a 12 V or 14 V battery (a low voltage battery) used for operating in-vehicle electronic circuits and illuminations, and for igniting an internal combustion engine. The other of them is a 200 V battery (a high voltage battery) for activating an electric motor when raised to a high voltage of 500 V to 900 V.
A power supply line for the low voltage battery is basically isolated from a power supply line for the high voltage battery. The electric motor provides a motor driver with control signals (pulse signals) from a microcomputer included in the in-vehicle electronic circuit. The motor driver controls operations of the vehicle. Detection signals (pulse signals) and so on from the motor driver are transmitted to the microcomputer.
Patent literature 1 discloses an invention in which an optical device is used to transmit the foregoing electric signals, the low voltage power supply line and the high voltage power supply line are isolated, and the electric signals are transmitted and received between high voltage and low voltage circuits.
Citation List
Patent Literature
Patent Literature 1:
    Japanese Patent Laid-Open Publication No. 2001-327171